Apparatus for removing liquid from fibrous materials

ABSTRACT

A APPARATUS FOR REMOVING LIQUID FROM A MIXTURE OF LIQUID AND FIBROUS MATERIAL IS PROVIDED FOR USE IN ACCOMPLISHING THE FIRST STAGE REMOVAL OF WATER FROM A SUGAR CANE PROCESSING A BY-PRODUCT KNOWN AS BAGASSE. THE APPARATUS IS GENERALLY CONSTRUCTED OF A LOWER PERFORATED CYLINDRICAL ROLLER WHICH IS PROVIDED WITH A PLURALITY OF OPENINGS ADAPTED TO RECEIVE WATER FROM THE BAGASSE, AN UPPER CYLINDRICAL ROLLER WHICH IS OFFSET FROM A VERTICAL ORIENTATION WITH THE LOWER ROLLER BY AN OFFSET ANGLE OF 30* TO 60* FROM VERTICAL, A SYSTEM FOR REMOVING WATER COLLECTED FROM THE WET BAGASSE, MOTOR DRIVE SYSTEMS FOR INDIVIDUALLY ROTATING THE UPPER AND LOWER ROLLERS AND CONVEYING SYSTEM FOR DELIVERING THE WET BAGASSE BETWEEN THE UPPER AND LOWER ROLLERS.

Oct-10, 1972 Q STEELE ETAL 3,697,324

APPARATUS FOR REMOVING LIQUID FROM FIBROUS MATERIALS Filed Oct. 2, 1969 4 Sheets-Sheet 1 Oct. 10, 1972 c, STEELE ETAL 3,697,324

APPARATUS FOR REMOVING LIQUID FROM FIBROUS MATERIALS 4 Sheets-Sheet z Filed 001;. 2, 1969 H H l|l IHII I J m, WW 6, 2

Oct. 10, 1972 c. R. STEELE ET AL APPARATUS FOR REMOVING LIQUID FROM FIBROUS MATERIALS Oct. 10, 1972 c. R. STEELE ErAL 3,697,324

APPARATUS FOR REMOVING LIQUID FROM FIBROUS MATERIALS Filed Oct. 2, 1969 4 Sheets-Sheet 4 United States Patent 3,697,324 APPARATUS FOR REMOVING LIQUID FROM FIBROUS MATERIALS Clarence R. Steele, Frank B. Price, and John M. Marshall,

Denver, Colo., assignors to CF&I Engineers, Inc., Denver, Colo.

Filed Oct. 2, 1969, Ser. No. 863,160

Int. Cl. 133% 3/04, 9/20; C13d 1/02 US. Cl. 1272 13 Claims ABSTRACT OF THE DISCLOSURE An apparatus for removing liquid from a mixture of liquid and fibrous material is provided for use in accomplishing the first stage removal of water from a sugar cane processing by-product known as bagasse. The apparatus is generally constructed of a lower perforated cylindrical roller which is provided with a plurality of openings adapted to receive water from the bagasse, an upper cylindrical roller which is offset from a vertical orientation with the lower roller by an oifset angle of 30 to 60" from vertical, a system for removing water collected from the wet bagasse, motor drive systems for individually rotating the upper and lower rollers and conveying system for delivering the wet bagasse between the upper and lower rollers.

This invention concerns an apparatus for removing liquid from a mixture of liquid and fibrous material and more particularly concerns an apparatus and method for removing water from a sugar cane processing by-product known as bagasse.

BACKGROUND OF THE INVENTION Various methods are known in the art for accomplishing the removal of sugar from raw sugar cane. In one such method, described in US. Pat. No. 3,248,263, issued Apr. 26, 1966, raw sugar cane is first cleaned to remove rocks and trash and then passed through preparation devices such as a cane buster and cane fiberizer which subdivide the sugar cane into a permeable mass. After the subdivided cane leaves the fiberizer it is passed over a scale for continuous weighing and subsequently introduced into a difiuser which causes sugar to be extracted from the cane. Exhausted cane, designated bagasse, emerges from the diifuser and is finally treated for rapid disposal. Since the by-product bagasse normally contains around 85 percent by weight water, a total reduction in the bagasse water content to approximately 50 percent by weight water permits the bagasse to be readily burned as fuel In other instances the dewatered bagasse can be processed into paper or board or returned to the soil as mulch.

Heretofore, the removal of water from the wet bagasse has been carried out with complex and expensive equipment, such as a three roller mill or French press. While the water content of Wet bagasse can be reduced to about 60 to 65 percent by weight in such equipment, the resultant bagasse still contains sufiicient water to prevent it from being burned as a fuel. In addition, the cost of using two conventional dewatering units in series is prohibitive. Accordingly, a low cost, efiicient method and apparatus was desired for initially reducing the water content of wet bagasse in a first stage so that ultimately the water content of wet bagasse could be reduced to 50 percent by weight or less with conventional equipment.

The new and improved apparatus and method of this invention makes possible the first stage reduction of water from the wet bagasse emerging from the difiuser so as to reduce the wet bagasse water content from about 85 per- 3,697,324 Patented Oct. 10, 1972 SUMMARY OF THE INVENTION An apparatus for removing liquid from a mixture of liquid and fibrous material is provided for use in accomplishing a first stage reduction in the water content of wet bagasse from about percent by weight water to about 70 percent by weight water. This separation apparatus is made up of at least a lower perforated cylindrical roller which has a plurality of individual openings adapted to receive water from the bagasse, an upper cylindrical roller which is otfset from a vertical orientation with the lower roller by an olfset angle of 30 to 60 from vertical, means for removing water collected from the wet bagasse from the interior of the lower roller, means for individually rotating the upper and lower rollers and conveying means for delivering the wet bagasse between the upper and lower rollers.

The first stage dewatering of bagasse accomplished in the apparatus of this invention makes it possible to further dewater the bagasse with conventional equipment until no more than 50 percent by weight water is present in the bagasse.

In addition to having fewer moving parts that conventional separation equipment, the apparatus of this invention has a lower installation cost, lower power requirements, is more easily maintained and operates at pressures of about 70 p.s.i.g. as compared to 1500 p.s.i.g. for

conventional separation equipment. The apparatus of the present invention also makes it possible to treat wet bagasse streams having large density variations, since the upper roller can be supported on independently pivotable arms which permit the continuous adjustment of the upper roller to density changes in the bagasse. Moreover, the shell of the upper roller can be filled with varying amounts and types of liquid so that the pressure transmitted by the upper roller is changed to meet varying process conditions. Lastly, the 30 to 60 offset arrangement of the upper and lower rollers and the orientation of the conveying means at an angle of about 42 to 45 from horizontal provides a distinct mechanical and processing advantage in the removal of water from wet bagasse.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will he better understood by reference to the drawings.

FIG. 1 is a top plan view of one form of wet bagasse dewatering apparatus suitable for practicing this invention.

FIG. 2 is a side elevation of the dewatering apparatus with the upper roller offset from a vertical orientation with the lower roller by an offset angle of 45 from vertical. In addition, FIG. 2 shows the wet bagasse conveying means disposed at an angle of 43 from horizontal.

FIG. 3 is an end elevation of the dewatering apparatus showing the upper roller in partial section.

FIG. 4 is an end elevation, partially in section, of the lower perforated roller.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is a plan view of a segment of the surface of the lower perforated roller.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, FIG. 1 shows upper roller which rotates on shaft 11 journalled in selfaligning adjustable bearings 14 and 15. The upper roller 10 is mounted on two independently pivota-ble arms 12 and 13 which support bearings 14 and 15. Lower roller 16 rotates on shaft 17 journalled in stationary bearings 18 and 19. The independently pivotable support arms 12 and 13 permit the upper roller 10 to adjust to density variations in the bagasse passing between upper roller 10 and lower roller 16 by providing for the pivoting movement of upper roller 16 about pivot point 21 at the end of the support arms.

Rotation of the upper roller 10 is accomplished by motor assembly 20 which drives sprocket 22 through chain 23 connecting sprokets 22 and 27. Sprocket 22 in turn rotates cross shaft 24 causing sprocket 25 at the opposite end of the cross shaft to drive the upper roller sprocket 29. Chain 31 interconnects sprockets 25 and 29. Similarly, motor assembly 60 is used to drive lower roller 16 by means of sprockets 28 and 26 interconnected by chain 30. Also shown in FIG. 1 are worm gear housings 32 and 33 for motor assemblies 20 and 60, respectively.

As can be seen in FIG. 1 lower perforated roller 16 isslightly wider-in length than upper roller 10 so that the upper roller can fit between rings 34 and 35 on the outer periphery of lower roller 16. The rings 34 and 35 are provided for lower roller 16 to assure that wet bagasse being passed between the upper and lower roller does not spill overthe side of lower roller 16. In addition, each end of lower roller 16 is provided with water deflector plates 36 and 37 to prevent water which enters the in terior of the lower roller from splashing onto bearings 18 and 19.

Both the upper roller 10 and lower roller 16 are provided with a series of reinforcing rings 39 and 40 to strengthen the outer working surfaces of the rollers. The interior of each roller is made up of a series of ribs in the form of plates 41, 42, 43, and 44 which are spaced about the longitudinal'axisvof each roller and which similarly strengthen the outer working surfaces of the upper and lower rollers. Two cone halves, shown as 45 and 46 for the upper roller and as 47 and 48 for the lower roller, are mounted on the plates 41, 42, 43 and 44 spaced about the longitudinal axis of each roller so as to define a barrel-shaped hollow chamber for each roller. Normally at least twelve plates, shown only as 41, 42, 43 and 44in the drawing, are spaced at equal distances apart, and surround each cone half in the upper and lower roller.

The wet bagasseto be dewatered is carried by feed conveyor 50 and dropped into feed chute 51. Feed chute 51 is provided with a plurality of small openings around its periphery so that free water in the bagasse can be removed prior to passage between rollers 10 and 16. During rotation of upper roller 10 and lower roller 16 water is squeezed out from the wet bagasse as it passes between the nipping surfaces of the rollers. The water squeezed out of the wet bagasse passes through openings 49 in the surface of the lower roller 16 and into the interior of the lower. roller. As water passes between the various plates 43 and 44 spaced about the longitudinal axis of the lower roller, it spills through opening 52 into collecting chamber 53 located at the bottom of the lower roller.- When water removed from the wet bagasse accumulates in collecting chamber 53, it can be easily removed by a pump. The bagasse which has been passed between upper roller 10 and lower roller 16 passes out onto conveyor 54 shown in FIG. 2 which is adapted for removal of dewatered bagasse.

As can be seen in FIG. 2, both the upper roller 10 and lower roller 16 are equipped with scrapers 55, and 56, respectively, to remove any fibrous bagasse or other mate-v rials which might collect on the surfaces of the rollers.

In addition, FIG. 2 shows the preferred orientation of upper and lower rollers 10 and 16 and feed chute 51. Up.- i

it is desirable in processing wet bagasse that the feed chute v 51 be disposed at an angle of about 42 to about 45 from t a horizontal orientation so that the wet bagasse material will have a tendency to slide down the feed chute as rollers 10 and 16 grip the material. Under normal operating conditions when the feed chute 51 is oriented at an angle less than 42 from horizontal, the bagasse material has a tendency not to freely slide down the chute but instead tends to develop a choke at the point where the material is fed onto the chute. Likewise,.when the feed chute 51 is oriented at an angle of 45 or greater from horizontal, the bagasse material tends to slide toward the rollers too rapidly and the resultant quantity of material presented to the rollers often exceeds the amount which can be processed. Consequently, the rollers tend to choke at feed chute angles of 45 or greater from a horizontal orientation. Accordingly it is desirable that the feed chute 51 be oriented at an angle of about 42 to about 45 from horizontal when bagasse is being dewatered. Preferably, however, when the feed chute is ori ented at an angle of about 43 from horizontal the wet bagasse material will not cause a choke at either the rollers or at the point where the material is fed into the chute.

It is understood, however, that extreme variations in bagasse density can alter the desired orientation of the feed chute.

Offset angle as defined herein means the angle measured between a vertical plane through thelongitudinal axis of the lower roller 16 and a plane formed by longitudinal axes of the upper and lower rollers 10 and 16. In FIG. 2, for example, upper roller 10 is shown at an offset angle of 45 from vertical.

FIGS. 4-7 provide a more illustrative example of a typical construction for the lower roller 16. As shown by FIGS. 6 and 7, the surface of lower roller 16 is provided with a plurality of openings 49 equipped to receive water removed from the wet bagasse. The openings 49 in the lower roller have a slightly smaller diameter at the top surface 57 of the roller shell than at the lower portion 58 of the roller shell. This sloping shape for openings 49 makes them self-cleaning during operation of the dewateringapparatus, e.g., water forced through the openings 49 removes any scale or bagasse residue collecting on the sides of the openings.

Moreover, FIGS. 4 and 5 show in detail the position of ring 34 on the outer periphery of the lower roller and water deflector plate 36 water passing through the lower roller from damaging the bearings for said roller. Reinforcing rings 40 and platm 44 and 59 used to strengthen the shell of the roller are also shown.

As can be seen from the drawing, water passing through openings 49 is directed into the compartmentalized chambers defined by the spaced plates 44 and 59 and then passed through openings 52 into the collecting chamber 53.

Since the shell of upper roller 10 can be filled with varying amounts and types of liquids, the pressure transmitted by the upper roller can be changed to meet varying process conditions. Hydraulic pressure transmitting liquid is introduced into the shell of the upper roller through a bolted hatch (not shown) in the side wall of the roller. The ultimate pressure transmitted to the wet bagasse passing between upper roller 10 and lower roller 16, therefore, results from both the normal weight of the upper roller 10 and its mounting plus the added weight of the liquid filling the upper roller. Thus, the upperroller can function as merely a hydraulic pressure transmitting means.

As previously mentioned, it is envisioned that the apparatus of this invention be used as a first stage removal device for dewatering wet bagasse emerging from a sugar cane dilfuser. US. Pat. No. 3,248,263, issued Apr. 26, 1966, describes a preferred process for removing sugar from raw sugar cane and accordingly is hereby incorporated by reference. In this process sugar cane is passed through various preparation devices which subdivide the cane into a permeable mass. The permeable mass of fiberized sugar cane is then introduced into a diffuser which extracts sugar from the cane. The exhausted cane leaving the diffuser is termed wet-bagasse and contains about 85 percent by weight water. The first stage removal of water is carried out in the apparatus of this invention at operating pressures of about 70 p.s.i.g. This first stage processing reduces the water content of the bagasse from about 85 percent by weight to about 70 percent by weight. Subsequently a second stage separation of water from the 70 percent by weight water containing bagasse is carried out in conventional equipment of about 1500 p.s.i.g. This second stage processing reduces the water content of the Wet bagasse from about 70 percent by weight to no more than 50 percent by weight water.

What is claimed is:

1. An apparatus for removing liquid from fibrous material using low pressures comprising,

a pair of arms each of which is independently pivoted on a support structure,

a pair of cooperating upper and lower cylindrical pressing rollers,

said upper cylindrical roller rotatably mounted on said pivoted arms for movements relative to said lower roller so that the apparatus can accommodate fibrous material of varying thicknesses,

said lower roller mounted on a stationary axis,

said upper roller offset from vertical orientation relative to said lower roller by an offset angle in the range from about 30 to 60 from vertical,

said lower roller having a perforate surface for the removal of the liquid pressed from the fibrous material,

feed means for introducing the fibrous material to said pressing rollers,

said upper roller adapted to contain liquid in order to exert pressure against said lower roller to remove at least a portion of the liquid in the fibrous material through the perforations in said lower roller, and

means for rotating said upper and lower rollers.

2. An apparatus as defined in claim 1 wherein said means for removing the liquid separated from the fibrous material includes means for conducting the liquid through at least one end of the lower cylindrical roller.

3. An apparatus as defined in claim 1 wherein said feed means is disposed at an angle from about 42 to about 45 from the horizontal orientation.

4. An apparatus as defined in claim 1 wherein said upper roller is offset in relation to said lower roller by an offset angle of about 45 from vertical orientation.

5. An apparatus as defined in claim 1 wherein said feed means is disposed at an angle of about 43 from a horizontal orientation.

extend generally horizontally from said support structure to said upper roller.

7. An apparatus as defined in claim 6 wherein said lower perforated roller is journaled in stationary bearings and said upper roller is journaled in adjustable bearings secured to said pivoted arms.

8. In an apparatus for pressing juice from wet bagasse, the combination comprising:

a lower cylindrical roller having a perforate surface to receive liquid from said fibrous material,

an upper cylindrical roller offset from said lower roller in order that the fibrous material transverses the nip between said rollers at a downwardly inclined angle, a pair of arms each of which is pivoted on a support structure for rotatably mounting said upper roller,

said upper roller offset from vertical orientation relative to said lower roller by an offset angle in the range from about 30 to about 60,

means for rotating each of said upper and lower rollers,

means for removing the liquid pressed from the fibrous material through at least one of the end walls of said lower roller,

feed means for delivering the fibrous material to said upper and lower rollers, and

said upper roller containing liquid in order to exert hydraulic pressure by said upper roller against said lower roller sufficient to remove at least a portion of the liquid in the fibrous material through the perforated surface in the lower roller.

9. An apparatus as defined in claim 8 wherein said arms are independently pivoted on said support structure with respect to each other.

10. An apparatus as defined in claim 8 wherein said lower perforated roller is journaled in stationary bearings and said upper roller is journaled in adjustable bearings secured to said pivoted arms.

11. An apparatus as defined in claim 8 wherein said feed means is disposed at an angle from about 42 to about 45 from the horizontal orientation.

12. An apparatus as defined in claim 8 wherein said upper roller is offset in relation to said lower roller by an olfset angle of about 45 from vertical orientation.

13. An apparatus as defined in claim 8 wherein said feed means is disposed at an angle of about 43 from a horizontal orientation.

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